The present invention relates to barium titanate semiconductor ceramic compositions and, more particularly, to novel barium titanate semiconductor ceramics with a high breakdown voltage.
It has been known that barium titanate is an insulator having high resistivity more than 10.sup.10 .OMEGA.. cm, and can be converted into semiconductor ceramics having resistivity of not more than 10.sup.6 .OMEGA.. cm by incorporating a minor quantity of one or more doping elements such as Bi, Nb, W, Ta, Sb, and rare earth elements thereinto. Barium titanate semiconductor ceramics possess a positive resistance-temperature characteristic that the resitivity thereof is abruptly increased in a certain temperature range, so that these semiconductor ceramics have been used for positive temperature coefficient thermistors (hereinafter called as PTC thermistors) useful as current limiter, current stabilizers, thermal controllers, thermostatic heating elements, etc.